Genetic and morphological evidence of a single species of bronze featherback (Notopterus notopterus) in Sundaland

The bronze featherback (Notopterus notopterus) is an iconic species of freshwater fish commonly found in South-East Asia and of great commercial and patrimonial importance. At present, the genus Notopterus comprises of two distinct species, Notopterus notopterus (Pallas, 1769) and Notopterus synurus (Bloch & Schneider 1801). On the Indonesian archipelago, genetic diversity and morphology of the bronze featherback were investigated for conservation purposes. The use of DNA-based species delimitation methods, applied to 165 Cytochrome oxidase I sequences of Notopteridae (121 belonging to N. notopterus), evidence a concordance between species and Molecular Operational Taxonomic Unit (MOTU) and the two species of Notopterus are recognized. In N. notopterus, 9 haplotypes are detected among the 121 sequences analyzed, and three are restricted to Sundaland. These three haplotypes had distinct geographic distribution with a haplotype observed in Java, Sumatra and Borneo, another haplotype restricted to South Sumatra and a third haplotype only found in Northern Sumatra. The analyze of 21 morphometric and 9 meristic variables revealed two groups within N. notopterus, which were only supported by subtle differences in measurements with overlapping distributions between groups. The present study supports the validity of Notopterus notopterus in Sundaland and the remarkable genetic continuity among populations across its range distribution.